Typically, high density flexible polyurethane foams have low thermal conductivities in the range of 0.02-0.04 W/(m-° K) in an uncompressed state. High density polyurethane foams have a tendency to trap heat and slowly diffuse heat through conduction and convection. In particular, high density memory foam has the tendency to “sleep hotter” than traditional flexible foam, due to reduced open void space within the foam. When a person lies down on a memory foam mattress surface, the foam open void space reduces during compression and reduces the potential for air migration within the foam. As foam compression increases, convective heat transfer decreases and conductive heat transfer increases.
In previous mattress heat dissipation methods, bedding manufacturers have modified flexible polyurethane foam layers with various surface modifications and through-body modifications such as channeling, convoluting, and punching holes in a mattress layer in order to allow more air to pass through the foam; thereby, heat is able to dissipate faster from the mattress due to more void space. Prior methods also include forced heat dissipation methods, such as using a ventilation fan to induce cooling or a heat pump to remove heat from a bed.
Prior patents do not teach adding highly thermally conductive solids to flexible polyurethane foam to increase the foam thermal conductivity and using said increased thermally conductive flexible polyurethane foam as one or more layers in a mattress or seating article. Rigid silicon carbide foam (ceramic foam) has previously been utilized for high temperature applications, especially for the aerospace industry, heat exchangers, and compact electronics cooling.
It would be useful and desirable to develop a flexible, open-celled polyurethane foam containing highly thermally conductive solids to achieve improved heat dissipation which may be used in mattresses, pillows, topper pads or seat cushions.